1. Field of the Invention
The present invention relates to an ink-jet print head, an ink-jet cartridge and an ink-jet printing apparatus equipped therewith which can produce high quality printed images on a print medium, and more specifically to an ink-jet cartridge and a method of storing a print head which are suitably applied to ink-jet printing that ejects onto a print medium print ink and a print performance improving liquid that makes insoluble or aggregates coloring materials in the print ink.
2. Description of the Related Art
Apparatuses that print (or record) on a print medium (or recording paper), including paper, cloth and plastic sheets such as OHP films, have been proposed to have a construction that can mount a recording head of various systems such as wire dot recording, thermosensitive recording, thermal transfer recording and ink-jet recording.
Of these recording systems, the ink-jet system is one of low-noise non-impact recording systems that eject ink which then directly adheres to the recording paper. The ink-jet system is largely classed, according to the ink droplet forming method and ink ejection energy generation method, into a continuous type (including charged particle control and spray systems) and an on-demand type (including piezo, spark and bubble jet systems).
The continuous type ejects ink continuously and imparts electric charge only to necessary droplets. The charged droplets then adhere to the recording paper and the remaining non-charged droplets are wasted. The on-demand type, on the other hand, delivers ink only when necessary for printing and therefore neither waste ink nor have a risk of contaminating the interior of the printer. The on-demand type, because it starts or stops ink ejection, has lower response frequencies than those of the continuous type. Hence, the on-demand type realizes high-speed printing by increasing the number of nozzles, and most of the recording apparatuses currently on the market are of the on-demand type. Because the recording apparatuses having the recording head of such an ink-jet system are capable of high-density and high-speed recording, they are commercialized and utilized as output means of information processing systems, which include printers as output terminals of copying machines, facsimiles, electronic typewriters, word processors and workstations or handy or portable printers used on personal computers, host computers, optical disk devices and video apparatuses. In this case, the ink-jet recording apparatus will take a configuration that meets particular functions and the conditions of use of these apparatuses.
Generally, the ink-jet recording apparatuses include a carriage mounting a recording means (recording head) and an ink tank, a feeding means to feed recording paper, and a control means to control these components. The recording head that ejects ink droplets from a plurality of nozzles is serially scanned, i.e., moved in a direction (main scan direction) perpendicular to the recording paper feeding direction (sub-scan direction) and at the same time the recording paper is intermittently fed by an amount equal to the recording width of the recording head during the non-recording time. This recording system performs recording by shooting ink droplets onto the recording paper according to recording signals and has found wide use because of its low running cost and low-noise operation. The use of the recording head that has many ink ejection nozzles aligned in the sub-scan direction can perform recording over a width corresponding to the number of nozzles by scanning, the recording head over the recording paper once. This makes it possible to increase the speed of the recording action.
In the case of a color ink-jet recording apparatus, a color image is formed by superimposing ink droplets ejected from multiple color recording heads. To perform color recording in general requires four kinds of recording head and ink cartridge that correspond to three primary colors-yellow (Y), magenta (M) and cyan (C) -or four colors including black (B) in addition to the three primary colors. In recent years, recording apparatuses that mount such three- or four-color recording heads to form full-color images have been commercialized.
The energy generating means in the recording head to produce energy for ejecting ink include one that uses electromechanical transducers such as piezoelectric elements and one that uses electrothermal transducers having heat generating resisters to heat liquid.
The recording head of a system (so-called bubble jet system) that ejects liquid by using thermal energy (which utilizes the film boiling phenomenon) can arrange the liquid nozzles in high density and thus perform high resolution recording.
The process of ejecting ink as performed by the bubble jet type recording head with the above construction will be explained briefly.
When a heat generating resister (heater) reaches a predetermined temperature, a film bubble that covers the heater surface is :formed. This bubble has a very high internal pressure and expels the ink in the nozzle. An inertia force produced by the expelling action forces the ink out of the nozzle and toward a common liquid chamber in the opposite direction. As the ink movement advances, the internal pressure of the bubble becomes negative and, combined with the flow path resistance, slows down a moving speed of the ink. The speed of the ink ejected out of an orifice of the nozzle is faster than that within the nozzle, so that the ink is narrowed by the balance of the inertia force, the flow path resistance, contraction of the bubble and ink surface tension, and a lump of ink outside the orifice is separated into a droplet. Simultaneously with the contraction of the bubble, ink is supplied from the common liquid chamber into the nozzle by a capillary action and stands by for the next pulse.
In this way the recording head that uses the electrothermal transducer as an energy generating means can produce a bubble in the ink in the liquid path in response to and in a one-to-one relation with a drive electric pulse signal and can also produce and contract a bubble instantaneously and properly, realizing ejection of ink droplets with excellent responsiveness. Further, the recording head can be made compact easily by taking full advantage of the IC technology and microfabrication technology in the semiconductor field where the technological advance and reliability improvement in recent years are remarkable. This in turn facilitates high density integration and lowers the manufacturing cost.
There are two types of such recording heads, a permanent type and a detachable type. In the permanent type the recording head has a service life longer than that of the recording apparatus and is so constructed that it is normally not removed from the apparatus itself. The detachable type, on the other hand, has a detachable head cartridge (also called an ink cartridge) in which a recording head and an ink tank are assembled together. When ink in the head cartridge runs out, the head cartridge is taken out of the apparatus body for recycling and a new head cartridge is installed.
The ink orifices of the head cartridge are sealed with a seal tape for protection during transport, storage and marketing of the head cartridge and also for preventing leakage or evaporation of ink from the ink orifices and inflow of air.
If the adhesion force of the seal tape is increased for more reliable prevention of ink leakage or evaporation and air inflow, adhesive agent of the seal tape remains on the periphery of the orifices. To avoid this problem, a method is known in which a cap member is installed on a seal tape having weak adhesion to press the seal tape by an elastic body of the cap member against the periphery of the orifices. There are growing demands for the ink-jet recording apparatus as excellent recording means and also for higher quality printed images.
In forming images on a recording medium called plain paper the conventional ink-jet recording apparatus has a problem of insufficient water resistance of the image. Another problem is that, when forming color images, it is difficult to provide images that are highly dense without feathering and bleeding between colors, in other words, color images that have both fastness and high print quality.
As a means to improve water resistance of an image, a method is known which uses ink that a colorant contained in the ink has a water-resistant property. This method has been put into practical use in recent years. The water resistance, however, is not good enough and because the ink is hardly soluble in water after being dried, the orifices of the recording head are easily clogged. Preventing this problem inevitably gives rises to another problem of making the apparatus construction more complex.
Japanese Patent Application Laying-Open No. 84992/1981 discloses a method wherein a material for fixing dyes to recording paper is applied to the recording paper beforehand and a large amount of such treated paper is prepared. With this method, however, it is necessary to use only the particular recording paper prepared beforehand for printing. Further, because the dedicated recording paper coated with a dye fixing material is produced in large amounts beforehand, a large dedicated paper making equipment becomes necessary increasing the overall cost. Moreover, it is difficult to coat the dye fixing material over the paper to a predetermined thickness stably during the process of making the dedicated recording paper.
Japanese Patent Application Laying-Open No. 63185/1989 discloses a technology wherein a colorless ink that makes a dye insoluble is ejected from an ink-jet recording head onto the recording paper.
Japanese Patent Application Laying-Open No. 202328/1993 discloses a technology that forms a water-resistant image without color bleeding by applying a multivalent metallic salt solution followed by an ink containing chemical dye having carboxyl group. When liquid that renders dyes insoluble is ejected from an ink-jet head, however, if the recording ink and the liquid should come into contact within the recording apparatus body, an operational failure of the recording apparatus may result. Any prior art offers no recording apparatus configuration that incorporates measures against such problems.
A number of technologies have been proposed that improve the fastness of printed images on a recording medium.
Japanese Patent Application Laying-Open No. 24486/1978 discloses a technique that transforms dyes into lake and fixes them on a dyeing medium by post-processing the dyeing medium to enhance their wet fastness.
Japanese Patent Application Laying-Open No. 43733/1979 in particular discloses a recording method that uses the ink-jet recording system and applies two or more ingredients that promote a film forming performance at normal or elevated temperatures when the ingredients contact. In a printed matter printed with this method, a film firmly adhering to the recording medium is formed as the ingredients contact each other on the recording medium.
Japanese Patent Application Laying-Open No. 150396/1980 (Japanese Patent Application Publication No. 38155/1987), too, discloses a method of applying a water-resisting agent that forms lake of dye after performing the ink-jet recording using aqueous dye ink.
U.S. Pat. No. 4,538,160 discloses an ink-jet recording method which identifies beforehand an image position where recording is to be made and shoots onto the same identified position a recording ink and a process ink for improving the quality and durability of a dot. Among other methods disclosed in this patent are one that describes an image using the process ink before applying the recording ink, one that superimposes the process ink on the image that has been described using the recording ink, and one that shoots the recording ink onto the pattern that has been described with the process ink and then applies the process ink again overlapping the described image.
On the other hand, in an ink-jet recording system, because the recording head ejects ink droplets onto a recording medium such as paper or OHP film, fine ink particles or mist other than the main ink droplets and splashes produced when the ink lands on the recording medium will adhere to that part of the recording head where the orifices are formed, accumulating solidified ink around the orifices. Further, foreign matters such as paper dust may stick to the accumulated ink. These will interfere with the ink ejection, causing such troubles as ink droplets being ejected in unexpected directions or failing to be shot out.
When a recording head, after being mounted in a printing apparatus, is left in a non-recording state where it does not eject ink for a long period, ink in the orifices will evaporate, increasing its viscosity or become dry or solidified, clogging the orifices, which in turn will result in a random-direction ejection or a failure to eject. Thus, the ink-jet recording apparatus is provided with a recovery means to eliminate these problems.
The recovery means commonly uses a wiping structure, which wipes an orifice-formed surface with a blade formed of an elastic member such as rubber to remove from the orifice-formed surface unwanted ink that was formed by accumulating mist and by the ink splashes from the recording medium and also remove foreign matters such as paper dust.
In the head cartridge having a head which ejects a print performance improving liquid that makes dyes (colorants) in the ink insoluble or aggregate, when an ink or a print performance improving liquid should leak from the orifices during transport, storage or marketing, or when ink mist other than the main ink droplets ejected during printing and ink splashes from the recording medium are produced in large amounts, or when inadequate recovery operation or wiping operation is performed, the ink and the print performance improving liquid will come into contact with each other on the orifice-formed surface of the head, causing the colorants (dyes) to become insoluble or aggregate near the orifices and foreign matters such as paper dust to stick to the colorants. These may hinder the ink ejection, giving rise to a risk of the ink droplets flying in random directions or failing to be ejected.
As to the above-mentioned troubles arising from the mixing of the ink and the liquid that makes ink insoluble or as to the construction to eliminate such troubles, no description or even suggestion is found in the above conventional arts.
The present invention has been accomplished to solve these problems and its object is to keep the dyes (colorants) from becoming insoluble or aggregating around the orifices of the head and thereby maintain high print quality even if the ink and the print performance improving liquid should leak from the orifices during transport, storage, marketing or use.
In a first aspect of the present invention, there is provided an ink-jet cartridge, comprising:
a print head portion having a first ejection portion to eject print ink and a second ejection portion to eject liquid containing print performance improving liquid to improve the print performance of the print ink ejected from the first ejection portion, the print head portion being able to be mounted in an ink-jet print apparatus; and
a seal member removably bonded to the print head portion and having an opening, the seal member closing the first ejection portion and the second ejection portion with the opening located between the first and second ejection portions.
In a second aspect of the present invention, there is provided an ink-jet cartridge, comprising:
a print head portion having a first ejection portion to eject print ink and a second ejection portion to eject liquid containing print performance improving liquid to improve the print performance of the print ink ejected from the first ejection portion, the print head portion being able to be mounted in an ink-jet print apparatus; and
an ejection portion pressing member removably mounted on the print head portion, the ejection portion pressing member having first and second elastic members, the first and second elastic members forming independent pressing surfaces to press the first and second ejection portions, respectively.
In a third aspect of the present invention, there is provided a method of storing a print head having a first ejection portion to eject print ink and a second ejection portion to eject liquid containing print performance improving liquid to improve the print performance of the print ink ejected from the first ejection portion, the print head being able to be mounted in an ink-jet print apparatus, comprising the step of:
hermetically closing the first and second ejection portions with first and second elastic members of a ejection portion pressing member, the first and second elastic members having independent pressing surfaces.
Here, the ejection portion pressing member may press the first and second ejection portions through a seal member that closes the first and second ejection portions.
The seal member may have an opening between a portion closing the first ejection portion and a portion closing the second ejection portion.
The first and second elastic members may be formed of a porous body.
A pressing surface of at least one of the first and second elastic members may have a smooth skin layer.
A pressing force of the second elastic member may be greater than a pressing force of the first elastic member.
A dimension of the second elastic member in a pressing direction may be set larger than a dimension of the first elastic member in the pressing direction to differentiate pressing forces of the first elastic member and the second elastic member.
The second elastic member may use a material with a higher hardness than that of a material of the first elastic member to differentiate pressing forces of the first elastic member and the second elastic member.
A rib may be provided between the first elastic member and the second elastic member, the rib having a height lower than the heights of the first and second elastic members when elastically deformed.
The second elastic member may be made of a material with excellent acid resistance.
The ejection portion pressing member may have a holding member that holds the first and second elastic members and keeps the first and second elastic members in an elastically deformed state produced by a pressing action, and the holding member may be provided with means, at a position between the first and second elastic members, for preventing liquid from at least one of the first and second ejection portions reaching the other ejection portion.
The reach preventing means may comprise a rib to isolate the first and second elastic members from each other.
The reach preventing means may comprise a groove or a finely roughened surface formed on the holding member between the first and second elastic members.
The reach preventing means may comprise a liquid-repellent surface applied on the holding member between the first and second elastic members.
The reach preventing means may comprise a liquid-absorbent member provided on the holding member between the first and second elastic member.
The above and other objects, effects, features and advantages of the present invention will become apparent from the following description of embodiments thereof taken in conjunction with the accompanying drawings.